Recent studies reveal that approximately 20% of patients with familial ALS (FALS) have a mutation of the gene that codes for the enzyme Cu/Zn superoxide dismutase (SOD). Although this mutation has not been demonstrated in sporadic cases, the striking phenotypic similarity between FALS and sporadic ALS suggests that a common pathogenesis may be present. Studies demonstrate that SOD is reduced by 50% in red blood cell lysates, lymphoblastoid lines and spinal cord anterior horn in patients with the mutation. CSF SOD is reduced by 65% in sporadic ALS Patients. These data and observations strongly suggest that deficient anti-oxidant capacity could play a significant role in the pathogenesis of ALS. Because of its physicochemical characteristics, SOD does not cross the blood brain barrier when given parenterally. Bovine SOD (bSOD) is a powerful anti-oxidant which is essentially non-toxic when given by several routes including intrathecal (IT).